This invention relates to the field of paper converting, more particularly to rewinding a web of paper into paper logs which are preferably relatively small diameter rolls of paper typically wound on cardboard tubular cores and suitable for cutting into short axial segments resulting ultimately in consumer-sized rolls of toilet paper or kitchen towels or the like. This rewinder log control is particularly suited for controlling the finished logs of soft rolls at high speed such as are produced by equipment as disclosed in U.S. Pat. No. 5,226,611, titled TWIN STATION REWINDER, the disclosure of which is hereby expressly incorporated herein by reference.
It has been observed that soft logs of bathroom tissue or kitchen towels act as out of balance flexible rotors when winding at high speed. During the winding process the log is contained between three rolls which provide very good control of the log. At the end of the winding process, the diameter control rolls open and the rotating log is released to fall into a log deceleration receiver. This system works well for unembossed "hard" logs which are relatively dense, rigid and dynamically balanced. Embossed logs are relatively soft, flexible and lightweight, resulting in unpredictable behavior when the diameter control rolls open, and the log is released to the log deceleration receiver. Left uncontrolled, such soft logs have been found to move out of a right cylindrical column and form an arc while still spinning and also to bounce out of the log receiver. One approach has been to reduce the winding speed to prevent damage to the outer sheets of paper on the logs and to assure the log will enter and remain in the receiver during deceleration. However, lower rewinding speeds result in less efficient production and consequent higher costs.
The present invention overcomes these difficulties by providing an improved structure and method of decelerating soft paper logs before delivery to the log receiver, permitting maintenance of high winding speeds and rapid and positive control of the logs after rewinding is completed and before the soft logs are released. The present invention includes a pair of log control fingers which are movable from a clearance position (maintained while the log is rewound) to a braking position in which the fingers trap the log and quickly bring it to a complete stop as the diameter control rolls open to release the finished log. The combination of continuous three roll contact throughout the winding process followed by containment in a cavity formed by the fingers resulting in rapid deceleration of the log in the winding area results in a satisfactory operation for winding soft logs at high speed. The log control fingers are located in grooves in the diameter control rolls, and remain below the surface of the diameter control rolls during the winding process where they have no effect on the winding process. At the completion of winding, the fingers are actuated out of the diameter control rolls and trap the log, bringing it to a stop before dropping it into the receiver. The fingers can be actuated by a cam or air cylinder or other suitable means. In a preferred embodiment, a cam is used which is adjustable to various diameter logs, with the adjustment available to the machine operator while the equipment is running. It has been found that stopping rotation of the log before delivery to the receiver reduces the design requirements for the receiver.